Heater for sealing carton containers

ABSTRACT

A heating apparatus for use with a carton forming machine for selectively heating the sealing surfaces of carton closure elements. A hot air distributor head is formed to receive the closure elements of the carton in adjacent relationship and to selectively heat portions of the closure elements by convection and radiation.

O United States Patent 1191 1111 3,724,093

Olila 1 Apr. 3, 1973 [54] HEATER FOR SEALING CARTON 3,405,505 10/1968Mistarz ..53 37s x CONTAINERS [75] Inventor: Howard E. Olila, St. Paul,Minn. Z' Examiner-Carri Dority &

tt F' H F b G tt [73] Assignee: Haskon Incorporated, Warsaw, Ind. omeymnegan en arson am my arm [22] Filed: Oct. 30, 1970 [57] ABSTRACT PPNil-185,805 A heating apparatus for use with a carton forming machinefor selectively heating the sealing surfaces of [52] CL 34/104, 53/375,93/441 GT carton closure elements. A hot air distributor head is 511 1m.01 ..F26b 25/00 formed to receive the closure elements of the carton 58Field of Search ..34/104, 105; 53/375; in adjacent relationship and toselectively heat p 93/44.l R, 44.1 GT tions of the closure elements byconvection and radiation. [56] References Cited 13 Claims, 5Drawing'Figures UNITED STATES PATENTS- 2,896,865 7/1959 Hamilton..239/598 X lit 9716f? PATENTEUAPR 3 I973 SHEET 1 BF 3 INVENTOR fin-MATTORNEYS HEATER FOR SEALING CARTON CONTAINERS This invention relates tocarton forming apparatus and more particularly to heating apparatus foruse with a carton forming machine for selectively heating the sealingsurfaces of carton closure elements.

Cartons made from scored paper blanks coated with a heat and pressuresensitive thermoplastic substance have been used for some time forpackaging fluids and other products. Milk, for example, is commonlymarketed in such paper cartons.

Various types of carton forming machines have been developed, andvarious types of heating arrangements have been used to heat the closureelements of the cartons prior to heat sealing them together. Althoughthese heating arrangements have served the purpose, they have not provedentirely satisfactoryunder all conditions of service.

For example, the use of gas heaters as described in U.S. Pat. No.3,364,826, is adequate for unlined paper cartons. However, metallic foillined cartons are now being used for the packaging of syrups and thelike where it is necessary to prevent the deterioration of the paper inthe carton or to prevent the paper from coming in contact with thecontents of the container. When such foil lined cartons are used, gasheaters, such as that described in US. Pat. No. 3,364,826, do notperform satisfactorily because the foil located nearest to the heater isoverheated and deteriorates before the portions of the carton furtheraway from the heater are adequately heated for sealing. Thus, there isan overconcentration of heat adjacent the outer ends of the cartonclosure elements, and proper uniform heating of the outer surfaces ofthe carton closure elements and of the foil lining is not attained.This, of course, has

those disclosed in U. S. Pat. Nos. 3,309,841 and 3,392,458 have beenused; however, these heaters are not adapted for satisfactory use withfoil-lined cartons because an excessive amount of heated air andradiation may act upon the inner foil lining of the carton so as to heatthe foil to an undesirably high temperature. Thus, as in the case of agas fired heater the inner foil may be so overheated that it melts awayfrom the inside of the carton closure members. This, of course, resultsnot only in a poor seal of the carton but exposes the contents of thecarton directly to the paper, and if the contents are such that theyreact in an unfavorable manner with the paper the integrity of thecarton may be destroyed and the contents thereof contaminated byportions of the paper cartons.

It is, therefore, an object of the present invention to provide animproved and efficient heater for use in carton forming machinesemploying metallic foil-lined paper board containers wherebypredetermined sealing surfaces of the carton closure elements areproperly heated to provide good seals when the heated closure elementsare pressed together.

Another object of the invention is to provide a heating apparatusemploying a unique hot air distributor head for selectively heating thesealing surfaces of carton closure elements by heated air convection andby radiation so, that the volume of heated air required is less thanthat required in prior art heaters.

Additional objects and advantages of the invention will be set forth inpart in the description which follows, and in part will be obvious fromthe description, or may be learned by practice of the invention. Theobjects and advantages are realized and attained by means of theinstrumentalities and combinations particularly pointed out in theappended claims.

To achieve these objects the present invention provides a heatingapparatus for use with a carton forming machine for selectively heatingthe sealing surfaces of carton closure elements. The heating apparatusincludes a hot air distributor head for heating the sealing surfacesby'heated air convection and by radiation, and also includes means inoperative relationship with the distributor head for positioning thehead adjacent to the carton closure elements and for introducing heatedair into the distributor head. The distributor head includes a firstplanar surface, first and second elongated hollow projections extendingsubstantially perpendicularly and in substantially the same directionaway from the first surface, each of the projections having an air flowpassageway therein for passing hot air against certain of the cartonsealing surfaces. A plurality of walls extend substantiallyperpendicularly and in substantially the same direction away from thefirst surface and form a substantially hour-glass like configuration.The distributor head further includes a cover positioned on the wallswhereby an open-ended chamber is formed by the cover and the walls, andthe walls further have apertures therein for directing heated airagainst surfaces of the carton closure elements.

It is to be understood that both the foregoing general description andthe following detailed description are exemplary and explanatory and arenot restrictive of the invention.

In the drawings:

FIG. 1 is a vertical fragmentary section of the heating apparatus,

FIG. 2 is a top plan view of the hot air distributor head;

FIG. 3 is a bottom plan view of the distributor head;

FIG. 4 is a top plan view of the heating apparatus with certain partsremoved for clarity; and

FIG. 5 is a side elevation view of the distributor head shown in FIG. 2.

With reference now to the drawings, wherein like reference charactersdesignate like or corresponding parts throughout the several views,there is shown in FIG. 1 a preferred embodiment of the invention. Thehot air distributor head of the invention is generally indicated by thenumeral 10. Similarly, the numeral 12 generally indicates means inoperative relationship with the distributor head for positioning thehead adjacent to carton closure elements 14 and for introducing heatedair into the distributor head.

Thedistributor head is illustrated in more detail in FIGS. 2-5 andincludes a first planar surface 16. The distributor head is preferablymade of metal having a high heat conductivity. A number of metals may beused, but analuminum-bronze alloy, e.g., ALUBRONZE" has been found toperform satisfactorily.

A first elongated hollow projection 18 and a second. elongated hollowprojection 20 extend substantially perpendicularly and in substantiallythe same direction away from the planar surface 16. First projection 18has an airflow passageway 22 therein and second projection 20 has anairflow passageway 24 for passing hot air against certain of the cartonsealing surfaces of closure elements 14.

A plurality of side walls 26 extend substantially perpendicularly and insubstantially the same direction away from planar surface 16 and arelocated in continuous relationship with respect to one another to form asubstantially hour-glass like configuration. As seen in FIG. 2, walls 26are formed integral with a top wall 28 to provide an open-ended chamber31 having a top 28 and side walls 26. In addition, the walls haveapertures 32 therein which are positioned at the interior acute anglecorners of the walls, and these apertures are directed upwardly andoutwardly from the walls so that heated air is directed against innercorners of closure elements 14 when the carton is positioned over thedistributor head.

Apertures 30 containing screws 34 or other adjustment means are providedin top wall 28 and extend across apertures 32 to adjust the flow of airthrough the apertures and provide the desired amount of heating of theinterior surface comers of the closure members.

First and second projections 18 and 20 are preferably parallel to eachother. A first baffle 36 (FIG. 2 and is fastened to the top of firstprojection 18 by screws 38 positioned in apertures 38 and second baffle40 is fastened to the top of second projection 20 by means of screws 42.These baffles are positioned adjacent to passageways 22 and 24, andshoulders 44 and 46 (FIG. 1) integral with first projection 18 and withsecond projection 20, respectively, combine with baf-'v fles 36 and 40to direct the flow of hot air inwardly from the projections and againstclosure members 14 of the carton. In this way the exterior surfaces oftwo opposing ones of the closure members are heated as the carton ismoved downwardly over distributor head and as it is removed from thedistributor head.

Apertures 32 are preferably located at angles of about 45 with respectto top wall 28 so that heated air is directed upwardly and outwardlyaway from walls 26 to heat the interior corners of closure members 14 asthe carton is placed over and removed from distributor head 10. Also aplurality of additional apertures 48 are provided adjacent to one of theapertures 32 and in one wall 26 for directing an additional volume ofheated air against the inner surface of one closure member 14. Thisclosure member frequently has an additional wall thickness as a resultof overlapping of the paper blank forming the tubular carton. Because ofthis additional wall thickness, apertures 48 are used to make sure thatproper heating of the interior surface of that closure member isaccomplished. As a result, proper heating of the interior and exteriorof closure members 14 is achieved and the bottom of the carton can befirmly sealed by pressing the closure members together at a later stepin the operation as is well known to those skilled in the art.

Slanted passageways 50 and 52 are provided in fluid communication withpassageway 22 and 24; respectively, to facilitate passage of hot airinto passageways 22 and 24 when distributor head 10 is positioned foroperation, as illustrated in FIG. 1. Furthermore, side walls 54 arefastened by screws orother conventional means 56 to opposite ends offirst and second projections 18 and 20 to assist in retaining the hotair within the distributor head'and to further heat closure members 14to provide the necessary melting of the thermoplastic coating.

In accordance with the invention, means are provided in operativerelationship with distributor head 10 for positioning the head adjacentto the carton closure elements and for introducing heated air into thedistributor head. As here embodied, the positioning and heated airintroducing means include hydraulic means for moving distributor head 10toward and away from the cartons to be sealed and the hydraulic meansinclude an hydraulic cylinder 58 of conventional construction having apiston 60 movable therein.

A-walled chamber member for receiving heated air is located in fluidcommunication with distributor head 10, and the walled chamber memberreceives heated air and directs the heated air into the distributorhead. As here embodied, the walled chamber member includes an outershell 62 and an inner shell 64 fastened to and spaced apart from theouter shell by means of spacer elements 66 to form a heat insulating airspace 68.

In accordance with the invention, means are positioned between thehydraulic cylinder and the walled chamber member for shielding thehydraulic cylinder from heat from the distributor head and from thewalled chamber member. As here embodied, the shielding means include aheat shield 70 comprised of a suitable heat insulating material attachedto outer shell 62 and positioned between the outer shell and hydrauliccylinder 58.

A coolant plate 72 having an essentially U shaped fluid flow passagewayformed by passageways 74, 75, and 74" is positioned between hydrauliccylinder 58 and heat'shield 70, and the U shaped passageway is in fluidcommunication with the interior 76 of the walled chamber via connections78 and 80. Coolant plate 72 performs the dual functions of shieldinghydraulic cylinder 58 from the heat in distributor head 10 and chamber76 and of pre-heating air entering the coolant plate from a supply line82. The air is preheated prior to entering heater 84, and the air isthen directed through connection 80 and through shells 62 and 64 to theinterior of chamber 76. The heated air then passes upwardly and intodistributor head 10 to ultimately pass into and through passageways 22and 24- and into chamber 31 and through apertures 32- and 48 to impingeupon closure elements 14 of the carton.

In order to provide stability of movement for distributor head 10 andfor piston 60, a base plate 86 is provided adjacent to hydrauliccylinder 58. The base plate may preferably be fastened by conventional 1means (not shown) to the hydraulic cylinder, and the base plate has anaperture 88 therein for receiving piston 60 and two apertures 80 forreceiving guide rods 90. Guide rods are connected to coolant plate 72 byconventional means (not shown), and these rods move through apertures 89with movement ofpiston 60'to stabilize the positioning of distributorhead 10.

In operation of the heating apparatus of this invention, a distributorhead 10 of suitable size,'depending upon the size of the cartons to beoperated'upon, is selected. Each of the distributor heads includes ativated in-a conventional manner to move head 10 up into adjacentrelationship with the carton s closure elements 14. During this upwardmovement of piston 60,

the distributor head should be secured to one or both of shells 62 and64 in a conventional manner.

The distributor head is provided with a shoulder 96 (FIG. 5) which fitsdown inside inner shell 64 (FIG. 1) so that shoulder 96 is in a positionclosely adjacent to the inside surface of shell 64. In addition, innershell 64 is provided with a flange extension 64', and surface 98 of thedistributor head rests on this flange extension when the distributorhead is placed in its operating position. v

With the distributor head in position, heater 84 is energized and aforced air source (not shown) is energized to provide a flow of air fromline 82 into U shaped passageway in coolant plate 72. The air thenpasses out through connection 78, into heater 84, and through connection80 into chamber 76. The air quickly fills chamber 76 and is then forcedupwardly into distributor head 10.

Slanted passageways 50 and 52 enable the hot air to pass upwardly andinto passageways 22- and 24 so that the air ultimately emerges from thepassageways adjacent to shoulders 44 and 46 and beneath baffles 36 and40. Simultaneously, air is forced upwardly into the central chamber 31to heat side walls 26 and top wall 28 and where it emerges throughapertures 32 and 48.

The flow of heated air, as just described, may be interrupted orcontinuous, and the interruptions may occur at various times in relationto the movement of the cartons and closure elements 14 with respect todistributor head 10. For example, the air could flow continuously as thedistributor head is moved to a position adjacent to closure elements 14and as the head is moved away from a position adjacent to the closureelements.

Alternately, the air could be caused to flow only during those periodsof time during which the closure elements are being moved downwardly andinto adjacent relationship with the distributor head. In this mode ofoperation, therefore, the air would cease to flow during those periodsof time when the closure elements are being removedfrom a positionadjacent to the distributor head. Still another alternative mode ofoperation would cause the airto flow and to impinge upon the closureelements only when the closure elements are being withdrawn from aposition adjacent to the distributor head.

Although these and other timing arrangements are envisioned by theinvention, the discussion herein will concern continuous flow of the airduring all phases of operation of the apparatus.

With a carton forming machine as shown in US. Pat. No. 3,364,826, afterthe bottom closure elements have been pre-broken and the mandrel wheelindexed to the bottom heating station, hydraulic cylinder 58- is acguiderods 90 also move in an upward direction through base plate apertures 88to stabilize the movement of the apparatus.

Because air is continuously flowing into chamber 76 and out throughpassageways 22 and 24 and through apertures 32 and 48, hot air is causedto impinge upon the entire outer surfaces of the two opposed gussetclosure panels 14' of the closure elements of the container as they passby passageways 22 and 24. In addition,

apertures 32 provide a continuous stream of heated air against theinterior corners of the closure elements and heated air from apertures48 impinge upon the doublewalled thickness of one interior corner of aclosure element.

Because the distributor head 10 is made of a highly heat conductivematerial, such as ALUBRONZE, the distributor head becomes quite hot.Thus, in addition to heating the closure elements by means of forced airconvection currents, the closure elements are also heated by means ofradiation from the hot metal of the distributor head.

Because of the large amount of heat present in chamber 76 and indistributor head 10, the heat shielding arrangement is preferablyprovided to shield hydraulic cylinder 58 and its associated hydraulicsystem (not shown) from the heat. This is accomplished by the use of airspace 68, which has an insulating effect, and is also accomplished bymeans of heat shield 70. Furthermore, coolant plate 72 acts to shieldcylinder 58 from the heat and also serves to preheat the air enteringvia line 82. The absorption of heat by this incoming air reduces theamount of heat that reaches cylinder 58 and also raises the temperatureof the air prior to its entering heater 84.

After the distributor head has reached its upper limit around theclosure elements 14, cylinder 58 is again energized by its hydraulicsystem (not shown) and piston 60 is retracted, again causing the hot airto impinge upon selected surfaces of the closure elements as thedistributor head is moved away from the carton. The time selected formovement of the head is set so that all necessary surfaces are uniformlyheated for sealing without degradation of the metal foil liner.

Because apertures 32 are positioned at an angle of approximately 45 withrespect to cover 28, hot air is forced up into the uppermost corners ofclosure elements 14 so that the desired heating of the inner foil liningis accomplished and so that a tight seal can be obtained when theclosure elements are pressed together in a later operational step, not apart of this invention. Additional apertures 48 arealso important indirecting an extra amount of air against the extra thickness of theclosure elements adjacent to one corner of the carton. This extrathickness is frequently referred to as the fifth wall of the carton andis created by overlapping of the paper, which is necessary to form thetubular carton.

When using metallic foil lined cartons it is extremely important tocarefully regulate the amount of heated air that impinges upon theinterior of the closure elements-so as to avoid excessive heating of thefoil. This is accomplished, in part, in this invention by means of ad'-justment screws 34 which may be rotated to permit more or less air toflow through apertures 32 and against the interior of closure elements14.

The substantially hour-glass shape of walls 26, as viewed in plan, issignificant since it permits the heated walls 26 to be immediatelyadjacent to closure elements 14' which after having been prebroken havean hour-glass configuration as is well known to those skilled in theart. Thus, radiation from walls 26, in addition to hot air convectioncurrents, acts upon the inner surfaces of the prebroken closure elementsto heat the foil lining or other lining of these elements to the desiredtemperature.

When a different size carton is to be formed, distributor head isremoved by placing a tool (not shown) into depressed area 92 and underbracket 94. The distributor head is then lifted off of inner shell 64and a different sized head is replaced.

The present invention thus provides a simple and effective heatingapparatus for heating the closure elements of carton containers prior tothe step of pressing the closure elements together to form a tight seal.

The invention in its broader aspects is not limited to the specificdetails as shown and described, and departures may be made from suchdetails without departing from the principles of the invention andwithout sacrificing its chief advantages.

What is claimed is:

l. A heating apparatus for use with a carton forming machine forselectively heating sealing surfaces of carton closure elements,comprising:

a hot air distributor head for heating saidsealing surfaces by heatedair convection and by radiation;

means in operative relationship with said distributor head forpositioning the headadjacent to said carton closure elements and forintroducing heated air into the distributor head and wherein said headincludes a first planar surface; I

first and second elongated hollow projections integral with andextending substantially perpendicularly and in substantially the samedirection away from said first surface, each of said projections havingan air flow passageway therein for passing hot air against selectedcarton sealing surfaces;

a plurality of walls integral with and extending substantiallyperpendicularly and in substantially the same direction away from saidfirst surface and forming a substantially hour-glass like configurationbetween said first and second projections;

a top wall integral with said walls whereby an openended chamber isformed;

' said walls further having apertures therein for directing heated airagainst surfaces of the carton closure elements; and

means in operative relationship with each of said apertures for enablingthe individual adjustment of air flow therethrough.

2. A heating apparatus as in claim 1 wherein said projections aresubstantially parallel to each other.

3. A heating apparatus as in claim 1 wherein said walls form fourinterior acute angle comers and wherein said apertures are located-ateach of said corners.

4. A heating apparatus as in claim 3 further including a plurality ofadditional apertures located adjacent to one of said corners and in oneof said walls for directing an additional volume of hot air against oneof the carton sealing surfaces and also including a pair of sidewallsfastened toopposite ends of said first and second projections to helpretain the hot air within the distributor head.

5. A heating apparatus for use with a carton forming machine forselectively heating sealing surfaces of carton closure elements,comprising:

a hot air distributor head for heating said sealing surfaces by heatedair convection and by radiation; means in operative relationship withsaid distributor head for positioning the head adjacent-to said cartonclosure elements and for introducing heated air into the distributorhead and wherein said head includes a first planar surface;

first and second elongated hollow projections integral with andextending substantially perpendicularly and in substantially the samedirection away from said first surface, each of said projections havingan air flow passageway therein for passing hot air against selectedcarton sealing surfaces;

a plurality of walls integral with and extending substantiallyperpendicularly and in substantially the same direction away from saidfirst surface and forming a substantially hour-glass like configurationbetween said first and second projections;

a top wall integral with said walls whereby an openended chamber isformed;

said walls further having apertures therein for directing heated airagainst surfaces of the carton closure elements;

hydraulic means for moving said distributor head toward and away fromcartons to be sealed;

a walled chamber member for receiving heated air and in fluidcommunication with the distributor head for'directing the heated airinto the distributor head; and means positioned between said hydraulicmeans and said chamber member for shielding the hydraulic means-fromheat from the distributor head and from the chamber member, saidshielding means including a heat shield attached to the chamber memberand between the chamber member and the hydraulic means; and

a coolant plate having fluid flow passageways therein in fluidcommunication with the interior of the chamber member, said coolantplate positioned between the hydraulic means and the chamber member forshielding the hydraulic means from the heat in the distributor head andthe chamber member and for preheating air as it passes into and throughthe coolant plate passageways on its way into the chamber member.

6. A heating apparatus as in claim 5 further including a heater inposition for heating air as it passes from the coolant plate passagewaysinto the chamber member.

7. A heating apparatus as in claim 6 wherein said hydraulic meansinclude an hydraulic cylinder and a piston movable therein, said pistonconnected to said coolant plate, and further including a base platehaving an aperture therein for slideably receiving the piston.

8. A heating apparatus as in claim 7 wherein said base plate has twoadditional apertures therein and wherein the apparatus further includestwo guide rods connected to the coolant plate and movably located withinsaid additional base plate apertures for stabilizing movement of thedistributor head.

9. A heating apparatus as in claim wherein said chamber member includes:

an outer shell; and

an inner shell fastened to and spaced apart from the outer shell to forma heat insulating air space.

10. A heating apparatus as in claim 9 wherein the distributor head fitsover said chamber member and wherein the interior of said inner shell isin fluid communication with the interior of the distributor head.

11. A heating apparatus as in claim 1 further including first and secondbaffles positioned adjacent the passageways in said first and .secondprojections, respectively, for directing the flow of hot air againstselected carton sealing surfaces.

12. A heating apparatus as in claim 1 1, wherein:

said air flow passageways extend longitudinally through said projectionsand terminate at top sur faces of said projections;

said baffles are mounted on said top surfaces of said projections; and

said projections include shoulders formed at said top surfaces toprovide inwardly extending passageways beneath said baffles fordirecting hot air to the carton sealing surfaces.

13. A heating apparatus as in claim 3 wherein said apertures arepositioned at angles of 45 with respect to said cover to direct hot airupwardly and outwardly away from said walls.

1. A heating apparatus for use with a carton forming machine forselectively heating sealing surfaces of carton closure elements,comprising: a hot air distributor head for heating said sealing surfacesby heated air convection and by radiation; means in operativerelationship with said distributor head for positioning the headadjacent to said carton closure elements and for introducing heated airinto the distributor head and wherein said head includes a first planarsurface; first and second elongated hollow projections integral with andextending substantially perpendicularly and in substantially the samedirection away from said first surface, each of said projections havingan air flow passageway therein for passing hot air against selectedcarton sealing surfaces; a plurality of walls integral with andextending substantially perpendicularly and in substantially the samedirection away from said first surface and forming a substantiallyhour-glass like configuration between said first and second projections;a top wall integral with said walls whereby an open-ended chamber isformed; said walls further having apertures therein for directing heatedair against surfaces of the carton closure elements; and means inoperative relationship with each of said apertures for enabling theindividual adjustment of air flow therethrough.
 2. A heating apparatusas in claim 1 wherein said projections are substantially parallel toeach other.
 3. A heating apparatus as in claim 1 wherein said walls formfour interior acute angle corners and wherein said apertures are locatedat each of said corners.
 4. A heating apparatus as in claim 3 furtherincluding a plurality of additional apertures located adjacent to one ofsaid corners and in one of said walls for directing an additional volumeof hot air against one of the carton sealing surfaces and also includinga pair of sidewalls fastened to opposite ends of said first and secondprojections to help retain the hot air within the distributor head.
 5. Aheating apparatus for use with a carton forming machine for selectivelyheating sealing surfaces of carton closure elements, comprising: a hotair distributor head for heating said sealing surfaces by heated airconvection and by radiation; means in operative relationship with saiddistributor head for positioning the head adjacent to said cartonclosure elements and for introducing heated air into the distributorhead and wherein said head includes a first planar surface; first andsecond elongated hollow projections integral with and extendingsubstantially perpendicularly and in substantially the same directionaway from said first surface, each of said projections having an airflow passageway therein for passing hot air against selected cartonsealing surfaces; a plurality of walls integral with and extendingsubstantially perpendicularly and in substantially the same directionaway from said first surface and forming a substantially hour-glass likeconfiguration between said first and second projections; a top wallintegral with said walls whereby an open-ended chamber is formed; saidwalls further having apertures therein for directing heated air againstsurfaces of the carton closure elements; hydraulic means for moving saiddistributor head toward and away from cartons to be sealed; a walledchamber member for receiving heated air and in fluid communication withthe distributor head for directing the heated air into the distributorhead; and means positioned between said hydraulic means and said chambermember for shielding the hydraulic means from heat from the distributorhead and from the chamber member, said shielding means including a heatshield attached to the chamber member and between the chamber member andthe hydraulic means; and a coolant plate having fluid flow passagewaystherein in fluid communication with the interior of the chamber member,said coolant plate positioned between the hydraulic means and thechamber member for shielding the hydraulic means from the heat in thedistributor head and the chamber member and for preheating air as itpasses into and through the coolant plate passageways on its way intothe chamber member.
 6. A heating apparatus as in claim 5 furtherincluding a heater in position for heating air as it passes from thecoolant plate passageways into the chamber member.
 7. A heatingapparatus as in claim 6 wherein said hydraulic means include anhydraulic cylinder and a piston movable therein, said piston connectedto said coolant plate, and further including a base plate having anaperture therein for slideably receiving the piston.
 8. A heatingapparatus as in claim 7 wherein said base plate has two additionalapertures therein and wherein the apparatus further includes two guiderods connected to the coolant plate and movably located within saidadditional base plate apertures for stabilizing movement of thedistributor head.
 9. A heating apparatus as in claim 5 wherein saidchamber member includes: an outer shell; and an inner shell fastened toand spaced apart from the outer shell to form a heat insulating airspace.
 10. A heating apparatus as in claim 9 wherein the distributorhead fits over said chamber member and wherein the interior of saidinner shell is in fluid communication with the interior of thedistributor head.
 11. A heating apparatus as in claim 1 furtherincluding first and second baffles positioned adjacent the passagewaysin said first and second projections, respectively, for directing theflow of hot air against selected carton sealing surfaces.
 12. A heatingapparatus as in claim 11, wherein: said air flow passageways extendlongitudinally tHrough said projections and terminate at top surfaces ofsaid projections; said baffles are mounted on said top surfaces of saidprojections; and said projections include shoulders formed at said topsurfaces to provide inwardly extending passageways beneath said bafflesfor directing hot air to the carton sealing surfaces.
 13. A heatingapparatus as in claim 3 wherein said apertures are positioned at anglesof 45* with respect to said cover to direct hot air upwardly andoutwardly away from said walls.